Cyclic ethers are polymerized by various means to give products of widespread utility. For instance, ethylene oxide is polymerized to polyethylene oxide which is useful for (in lower molecular grades) ceramics, cosmetics, lubricants, polyurethanes, (and in higher molecular weight grades), packaging film, denture adhesives, lubricants, and flocculation, and tetrahydrofuran (THF) is polymerized to poly(tetramethylene ether) glycol which is useful in the preparation of Spandex fibers, polyurethane resins useful in elastomeric parts, and thermoplastic elastomers useful for molding various mechanical parts. Therefore, improved methods of making these polymers are sought.
One general method for the polymerization of cyclic ethers is the so-called cationic mechanism. In this type of polymerization, an acid, usually a Bronsted or Lewis acid, is used as the catalyst. Accelerators (sometimes also called co-catalysts) are sometimes used, and these can affect both the rate and yield of the polymerization, as well as the structure (for example end groups) of the polyether produced. Disclosed herein is a new class of accelerators for the cationic polymerization of cyclic ethers.
J. S. Hrkach, et al., Macromolecules, vol. 23, p. 4042-4046 (1990) describe the polymerization of tetrahydrofuran using trimethylsilyl trifluoromethanesulfonate as the catalyst.
German Patent Application 2,459,163 describes the polymerization of THF using a combination of ferric chloride and carboxylic anhydride as catalyst.
U.S. Pat. Nos. 5,084,586 and 5,124,417 describe the cationic polymerization of various monomers, including cyclic ethers, using onium cations, whose corresponding anions are fluororalkylsulfatometallates. Onium ion catalyzed cationic polymerizations are well known cationic polymerizations.
Japanese Patent Application 51-82397 describes the polymerization of tetrahydrofuran using a combination of fluorosulfonic acid and a carboxylic acid as catalysts.
T. Misaki, et al., Nippon Kagaku Kaishi, p. 168-174 (1973) report on the polymerization of THF using a combination of metal aceylacetonates and acetyl chloride.
With the exception of J. R. Hrkach, et al., none of these references mentions the use of silicon compounds as catalysts or accelerators in the polymerizations.